And lynn a



R.-F. BRACKE.

VACUUM FEED CARBURET ER.

APPLICATION FILED JUNE 19. 1920.

1,370,944, Patented Mar. 8, 1921;

1 19 Y 3 l M/ t Mg berfffirac/re UNITED STATES PATENT OFFICE.

ROBERT F. BRACKE, OF CHICAGO, ILLINOIS, ASSIGNOR TO CURTIS 1B. CAMP,.OF CHICAGO, ILLINOIS, AND LYNN A. WILLIAMS, 0]? EVANS'ION, ILLINOIS,

JOINT TRUSTEES.

VACUUM-FEED CARBURETER.

Specification of Letters Patent.

Application filed June 19, 1920. Serial No. 390,070.

T 0 all whom it may con cern Be it known that I, Ronnn'r F. Bniiokn, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Vacuum-Feed Carbureters, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying draw ings, forming a part of this specification.

My invention relates to vacuum feed carbureters and has for its general object the provision of improved means for feeding fuel from a supply reservoir to a carbureter located above the reservoir.

' A further object of the present invention resides in the provision of a vacuum feed carburetor operable in connection with a one cylinder engine in which the intake inanifold is under suction only a small portion of the time, though the invention is not limited to use on this class of engines.

My invention has the further object of utilizing variations in suction caused by changes in the height the fuel has to be lifted to control a restriction in the fuel passage so that the constant level feature of the usual float chamber may be eliminated, without a. consequent variation in fuel and air proportions due to changes in fuel lift.

Although the present invention may be applied to various types of engines and carbureters, it finds particular utility when used in connection with a constant speed engine, and I have therefore illustrated a carbureter of this type in the accompanying drawings.

In the drawings: I

Figure 1 is a side elevational view of carbureter embodying the various improvements of my invention;

Fig. 2 is a longitudinal cross sectional view of the carbureter shown in Fig. 1 with the engine governor attached;

Fig. 3 is a cross sectional view taken along the line 3-3 of Fig. 2, looking in the direction indicated by the arrows, the governor being omitted;

Fig. 4 is an end view of the carbureter showing the choke mechanism, and

Fig. 5 is a. partial section taken on the line 5-5 of Fig. 1-

Similar characters of reference refer to similar parts throughout the several views.

Referring first to Figs. 1 and 2, 5 designates the main casing provided with a flange 6 arranged for attachment to the intake manifold of an internal combustion engine. Extending longitudinally through the casing 5 is an air passageway 7, forming a mixing chamber shown at 8. A throttle shaft 9 extends through the mixing chamber and supports a throttle 10. The outer end of the throttle shaft carries the throttle arm 11, connected with a rod 12. This rod is controlled by a centrifugal governing mechanism driven by the engine supplied with fuel from the carbureter and serves to vary the position of the throttle 10 and its associated baiile' 1.9, such that the speed of the engine is maintained substantially constant for all load and idling conditions.

This governor mechanism l2 may be of any suitable form but is here shown as of a well known structure suitably driven by the engine and in which rotation at decreased speed due to increase of engine load causes the rod 12 to move downwardly to open the throttle'lO and withdraw the baffie 19. p

Forming part part of the passageway 7 and screw-threaded into the casing 5 as shown, is a venturi 13 provided with a throat 14. The throat portion of the venturi contains a plurality of fuel ducts 15 affording communication between the throat and the annular chamber shown at 16. In the preferret form of the invention the throat is stepped or suddenly enlarged, as shown, it having been found in practice that the local suction is increased by a sudden enlargement just at the point of admission of the liquid fuel.

Carried by the venturi 13 is a spider 17 ar-anged to support the bafile 19 pivoted to and operable with the throttle 10. This baflle is peculiarly shaped as shown to cooperate with the venturi 13 in producing a very high suction at the throat 14. The spider 17 preferably made in the form of a punching having two or more slender spokes may be secured to the venturi in any suitable manner as by a C spring 18 sprung into a groove as shown in Fig. 2.

Attached to the air intake end of the carburetor in any suitable manner is a cap 20 provided with two air intake openings shown at 21 and 22in Fig. 4. Extending outwardly from the center of the cap 20 is a screw 23 serving as a pivot for a choker or valve 24, provided with air openings and 26 arranged for registration with the air intake openings 21 and 22 of the cap 20. A spring 27 is interposed between the head of the screw and the choker for the purpose of holding the choker flat against the cap. The main casing 5 carries a downwardly extending portion 28, to which is secured a sylphon 29. This sylphon is made up of thin material and is arranged for expansion and contraction for the purpose of regulating the mixture for different lifts, as will be pointed out hereinafter. Extending through the portion 28 and communicating with the interior of the sylphon is a fuel intake ort 30 adapted for connection with a pipe leading to the low level fuel reservoir. The lower part of the sylphon communicates with a fuel duct 31, leading to a chamber 32 in which is located a check valve 33. Communicating between the chamber 32 and the annular space 16 around the venturi is a fuel metering duct 34, into which extends a metering pin r A spring 36 is interposed between the easing 5 and the head of the pin and serves to hold the pin against the adjusting screw 37 carried by the lever 38. This lever is pivoted to the casing at 39 and has its lower end in contact with the free or movable end of the sylphon.

Communicating between the air passage way 7 and the sylphon 29 is the duct 40, 41, 42, in which is disposed a ball valve 43, seating against pressure in the sylphon.

The operation of the device is as follows: In starting, the choker 24 is moved to the right (Fig. 4) until the air ports 25 and 26 are moved out of alinement with the ports 21 and 22, this preventing the entrance of air into the carbureter. The engine is then cranked, producing a high suction in the passageway 7 This high suction is communicated to the sylphon through the duct 40, 41, 42 and serves to lift the initial fuel from the supply reservoir.

After the engine has started, the choker is moved to the left (Fig. 4), to permit the intake of air.

If the engine is idling, the governor mechanism connected with the rod 12 moves the throttle to the position shown in Fig. 2, thus placing the bafiie Well within the throat of the venturi, and producing a high velocity past the fuel ducts at the throat. This high velocity and venturi action produce a high suction at the throat and cause the fuel to pass from the sylphon through the duct 31, check valve 33, metering duct 31, and chamber 16 into the throat. The high suction thus produced in the sylphon seats the ball valve 43, and prevents back draft through the duct 40, 41 and 42.

When a load is placed on the engine its speed is slightly decreased, the throttle is the baflie from the throat of the venturi in response to a decreased engine speed results in a greater throat area without changing the venturi shape necessary to produce the required suction at the throat. As the load is further increased, the throttle is opened proportionally and the baffle withdrawn to a greater extent until the full load is reached when the throttle assumes the fully open position. Or if during operation the load on the engine is decreased the governor 12 automatically closes the throttle 10 and causes the baflie 19 to be inserted a corresponding distance into the venturi tube 14 thus cutting down the fuel mixture to take care of this change of load condition and maintain the engine speed substantially constant. If then the entire load is suddenly removed, the governor moves the throttle and baflie back to the position shown.

From the foregoing it will be seen that all variations in load which would ordinarily cause considerable change in engine speed are automatically taken care of to maintain a substantially constant engine speed without the necessity of manual op eration of any of the parts.

It will be noted also by reference to Fig. 2 that whenever the load on the engine is increased as above mentioned, and the en gine speed in response thereto starts to slow up, the governor 12 correspondingly opens the throttle 10 and withdraws the baffle 19 a corresponding distance from the throat of the venturi 14, thus admitting, as above stated, a greater engine suction to the mixing chamber 8, and permitting a greater quantity of fuel mixture to. flow through the Venturi tube which has been thus enlarged. Now the reason this opening of the throttle results in a greater suction in the mixing chamber 8 at a time when the engine is tending to slow down, and at a time when the opening in the Venturi tube has been enlarged by the corresponding withdrawal of the bafiie therefrom, is because a corresponding movement of the throttle and the baffle does not represent a corresponding opening at the throttle and at the Venturi tube, due to the straight walls surrounding the throttle, and the oblique walls of the Venturi tube with which the shape of the baffle conforms, and into which it fits. That is, a slight movement of the throttle along its parallel Walls increases the an increased engine suction distance of eight feet.

in the Venturi tube very little in comparison.

For this reason a much wider admis sion to engine suction has been created at the throttle than has been created at the Venturi tube, resulting in, as above stated, under such conditions in the mixing chamber 8 and a resulting increased flow of fuel mixture through the relatively slightly increased Venturi tube opening, which takes care of the additional load and maintains the speed of the engine constant under the new load conditions. The baffle should be shaped with reference to the Venturi tube, and this has been determined by experiment, so that it will create at the Venturi tube just the ri ht suction to give a perfect mixture of air and gasolene for every condition of engine load, and consequently for every slight change in opening or closing of the throttle due to change in engine speed.

Referring now to Fig. 3 which shows the compensation mechanism for maintaining the correct mixture for various lifts, let us assume that the carbureter is lifting fuel a Under these conditions the interior of the sylphon 29 is subjected to a reduction of pressure which is equivalent to that necessary to lift fuel eight feet. This results from the fact that there is free passage for fuel from the low level source of supply but restrictive passage for fuel from the sylphon to the venturi throat. This reduction of pressure produces a shortening or contractionof the sylplion 29 and a corresponding withdrawal of the metering pin .35. As the level of fuel in the reservoir is lowered, through the consumption of fuel or otherwise, the suction in the sylphon is increased with the result that'the metering pin 35 is withdrawn to a greater extent to maintain the correct mixture. If the'level of the supply tank is raised from'the low level the sylphon 29 expands and moves the metering .pin 35 in, to restrict thepassage of fuel terior to the venturi and a battle connectedwith said throttle valve'and arranged for movement within the venturi in each direction by the movement of the throttle valve.

2. In a vacuumfeed carbureter, the combination of a casing provided with a single air passageway, a venturi in said passageway and arranged to receive all the air pass ing therethrough, said venturi being provided with a fuel duct, and a bafile arranged for movement within the venturi and a speed governor for controlling the position of the bafiie.

In a carbureter, the combination with an induction passage, a Venturi tube therein,

a fuel inlet near the throat of said Ven- 4.111 a carbureter, a throttle shaft, a

Venturi tube, a guide anterior to the Venturi tube, a fuel inlet near the throat of said Venturi tube and axially alined therewith, a

battle pivotally supported between an eccentric extension from said shaft and said guide and adapted to be moved along the Venturi tube as the throttle shaft is rotated to open and close the throttle.

5. In a carburetor, the combination with an engine driven governor, a pair of valves serially arranged in the air passage through said carbureter, means connecting each of said valves with said governor, whereby said governor controls the size of the air passage at each valve, the valve nearer the engine being arranged to enlarge its opening more rapidly than the valve further from the engine each in a fixed relation to the other, whereby the velocity of air past the valve further from the engine is increased with the opening of said valve, and means to admit fuel to said carburetor at the region restricted by said valve further removed from the engine.

6. In a vacuum feed earbureter for internalcombustion engines, the combination of a casing having an air passageway extending tlierethrough, a venturi in the passageway, av baffle for the venturi arranged ior longitudinal movement within the latter,

- and means, controlled by the speed of the engine, for operating said baille forthe purpose of regulating the velocity of air passing through the venturi.

7. In a vacuum feed carbureter, the combination of a casing having an. air passageway, and a fuel discharge port emptying into the passageway, a valve for regulating the flow of fuel through the port, and suction operable means regulated by the height of the fuel lift for controlling the operation of said valve.

8. In a vacuum feed carbureter, the combination of a casin having an air passageway, and a fuel ischarge port emptying into the passageway, a valve for regulating the flow of fuel through the port, a suction chamber, a low level source of fuel, an unrestricted fuel passage leading from the low level source to said fuel discharge port, said suction chamber receiving suction from the fuel feed line between the fuel supply source and said fuel discharge port, and means operable by the suction produced in said chamber for controlling the operation of said valve.

9. In a vacuum feed carbureter, the combination of a casing having an air passageway, a venturi therein, said venturi being provided with a fuel port, a valve for controlling the fiow of fuel through said port, and a sylphon deflected under control of the fuel lift and operatively connected to the fuel line between the port and fuel supply,

for operating said valve.

10. In a vacuum feed carbureter, the combination of a casing having an air passage way, a choker'for said passageway, a venturi having a fuel port, a valve for controlling the flow of fuel through said port, a sylphon in the fuel feed line between the port and fuel supply for operating said valve, and a check valve between the sylphon and passageway for the purpose of lifting the initial fuel.

11. The combination with a carbureter, of a low level source of supply, a fuel pipe leading from the low level source of supply to the carburetor, a casing having an air passageway, a fuel discharge port connect inn the fuel line with the air passageway, a ba e for regulating the flow of air past the port, a governor controlled by the speed of the engine supplied by the carburetor, means mechanically connecting said governor with said bafile for controlling its position, a throttle also controlled by said governor, the battle and its housing being of such shape and proportions as to maintain suction at said port sufficient for lifting fuel from said low level source of supply for every speed and power condition of the engine.

12. The combination with a carbureter, of a low level source of fuel supply, a Venturi tube within the carbureter, a fuel discharge port in the wall of said Venturi tube, a pipe extending from the low level source of supply to the fuel discharge port in said Venturi tube, a baffle movable longitudinally in said Venturi tube to regulate the velocity of air therethrough, a speed governor driven by the engine supplied by the carbureter, means connecting said governor with said baflle for regulating the position of said baflle in said Venturi tube, said bafile and Venturi tube being of such shape and the movement by said governor being such that for all speed and power conditions of the engine sufficient suction will be maintained at the ort in said Venturi tube to lift fuel from tiie low level source of supply and to maintain a proper explosive mixture of fuel and air.

13. The combination with a carbureter for internal combustion engines of the type providing intermittent intake suction, of a low level fuel supply source, a fuel delivery port in the carburetor, a pressure regulated device connected with the fuel line between the fuel port and said low level source, a fuel valve in the fuel line between the pressure regulated device and the port, said fuel valve being regulated as to position by the pressure regulated device, and a check valve also in the fuel line between the fuel port and said pressure refgulated device, for preventing the relief 0 pressure on said pres sure regulated device and a consequent partial closure of the fuel port between suction strokes of the engine.

14. In combination with an engine fuel intake passage, of a Venturi tube having fuel ports therein and arranged for feeding air and fuel to said passage, a low level fuel supply source connected with ports in said Venturi tube, a valve for controlling the size of the fuel opening between said source and said ports, means operable responsive to the fuel lift for enlarging the fuel opening when the fuel lift is increased, and for decreasing the fuel opening when the fuel lift is decreased.

15. In combination with the intake passage for anen-gine ing intermittent suction, of a Venturi tube having fuel ports therein and arranged for feeding air and fuel to said a low level fuel supply source connected with ports in said Venturi tube, a baflfe within said Venturi tube for controlling the velocity of the air through said tube, a needle valve for controlling the size of the fuel openiq between said source and said ports, mum-operable responsive to the fuel 11ft, far the fuel opening when the fuel lift is increased, and for decreasing the fuel openingwhen the fuel lift is decreased, and: a check valve between said needle valve and the needle valve controlling means, for preventing said needle valve valve for controlling the size of the fuel opening between said source and said ports, and means including a check valve appurtenant to said needle valve, for maintaining a substantially constant suction in the fuel line during cessation of the suction in the engine intake passage at said ports.

In witness whereof, I hereunto subscribe my name this 14th day of June, 1920.

ROBERT F. BRACKE.

Witnesses WARREN DEwEs, EUGENE STUART. 

